Final answer:
The most comfortable position for a person who has trouble breathing when lying flat is the semi-Fowler's position. This position involves elevating the head and upper body to a 45-60-degree angle.
Step-by-step explanation:
The most comfortable position for a person who has trouble breathing when lying flat is semi-Fowler's position (c). This position involves elevating the head and upper body to a 45-60-degree angle. It helps to improve breathing by reducing the pressure on the chest and allowing the lungs to expand more easily. An example of this position is using pillows to prop yourself up in bed.